Laminated prestressed beam construction



May 17, 1966 P. J. STRIMPLE 3,251,152

LAMINATED PRESTRESSED BEAM CONSTRUCTION Filed Jan. 25, 1962 has; ZVQ/O 6 0 INVENTOR.

72 p/zecz a drew/ 15 ATTORNEYS United States Patent 3,251,162 LAMINATED PRESTRESSED BEAM CONSTRUCTHGN Pierce J. Strimpie, 9381 Dry Fork Road, Harrison, Ohio Filed Jan. 25, 1962, Ser. No. 168,613 3 Claims. r31. 52-223) This invention relates to a laminated reinforced beam or girder construction and has as its primary object the provision of an improved beam, joist or rafter characterized by extreme strength in relation to its Weight.

A further object of the invention is the provision of a beam of this character which may be constructed of a plurality of transverse laminations of boards, plywood, planks, or the like, of different lengths if desired, with the joints of the boards in end abutting relation being staggered relative to the transverse laminations.

An additional object of the invention is the provision of a beam of this character which is provided with a longitudinally extending reinforcing rod or cable having tensioning means at either end for suitably tensioning the same, after the formation and positioning of the beam.

An additional object of the invention is the provision of such a beam which may be made in any desired length, height, or thickness, and with any desired number of re inforcing rods or cables extending therethrough in accordance with the usage to which the beam is to be put.

Still another object of the invention is the provision of a beam of this character which is extremely sturdy and durable in construction, reliable and efiicient in operat-ion, and relatively simple and inexpensive to manufacture.

Still other objects reside in the combinations of elements, arrangements of parts, and features of construction, all as will be more fully pointed out hereinafter and disclosed in the accompanying drawings wherein there are shown preferred embodiments of this inventive concept.

In the drawings:

FIGURE 1 is a fragmentary side elevational view, partially broken away, of one form ofbeam constructed in accordance with the instant invention;

FIGURE 2 is an end elevational view of the beam of FIGURE 1 as viewed from the right;

FIGURE 3 is a sectional view taken substantially along the line 3-3 of FIGURE 1 as viewed in the direction indicated by the arrows;

FIGURE 4 is a view similar to FIGURE 1 showing a modified form of construction;

FIGURE 5 is an end elevational view of the beam of FIGURE 4;

FIGURE 6 is a view similar to FIGURES 1 and 4 showing a still further modified form of construction;

FIGURE 7 is an end elevational view of the beam of FIGURE 6;

FIGURE 8 is a multiple view showing certain alternative construction details of the reinforcing rod, which may be employed with any of the beams of the previous figures;

FIGURE 9 is an end elevational view of a beam having horizontal laminations; and

FIGURE 10 is a fragmentary side elevational view of a structure similar to that of FIGURE 9 provided with a further modified form of end cap.

Similar reference characters refer to similar parts throughout the several views of the drawing.

Having reference now to the drawings in detail, and more particularly to FIGURE 1, the beam of the instant invention is generally indicated at 10, and comprises a plurality of layers or laminations 11 of wood, plywood, or similar material, which may be glued, cemented, bolted or secured together by screws, as desired. It is to be understood that the several laminations may be made up of a plurality of lengths of end to end positioned boards, planks or plywood with the joints staggered lengthwise. It is also to be understood that any desired number of laminations may be employed and of any desired height or thickness.

In the modification of FIGURE 1, a single reinforcing rod 12 is extended from the upper portion of one end of the beam downwardly at an angle to a midpoint of the beam where it is held in its lowermost position by a dowel or pin 13. The pin 13 may extend entirely across the several laminations, or may terminate interiorly of the outermost lamination so as to leave a smooth outer surface for decorative purposes, it being understood that the rod 12 and the pin 13 are positioned interiorly of the laminated structure during the formation thereof. A transverse or horizontal board or plank 14 is preferably secured on the bottom of the beam for the proper align ment of the laminations during assembly.

After the reinforcing rods 12 have been suitably positioned in the beam, and the laminations secured together in any desired manner as previously stated, a metallic end cap 17 is positioned over the upper corners of the beam at each end. The cap includes triangular side plates 18, and a rectangular end plate 19, and a top plate 22, suitable bolts or screws 21) being provided to hold the end cap in position on the upper end corner of the beam. A rectangular recess 21 is formed in the end cap, the laminated beam being previously cut to accommodate the same. The bottom of the recess 21 is parallel to the diagonal from the lower transverse side of the end plate 19 to the rear transverse side of the top plate 22, that is parallel to the plane through the hypotenuses of the side plates 18-18. The end of the rod 12 extends outwardly through a suitable opening centrally positioned in the recess 21. The bottom of the recess 21 is inclined at an acute angle with respect to the end plate 19, such that the end of the-reinforcing rod 12 is received through the hole in the bottom at approximately a right angle with respect to the latter. The outer end of the rod 12 is threaded, and a suitable tensioning nut 23 is positioned thereon. Obviously, by tightening the nuts 23 during the formation of the beam, at relatively high tension may be applied thereto effectively to strengthen the beam and retain the laminations in assembled relation.

A modified form of construction is shown in FIGURE 4 wherein a beam 25 is comprised of a plurality of laminations 26 and a bottom plank 27 similar to that previously described, but wherein a pair of rods or cables 28 are empolyed and passed beneath suitable dowels or pins 29. The end cap 30 is similar to the end cap 17 previously described and includes side plates 31, a top plate 32, and an end plate 33, the plates being held in position by bolts or screws 34. A recess 35, is provided but here extends the full width of the end plate 33 and has accommodations for a pair of spaced apart reinforcing rods 12, which are secured in position by tensioning nuts 23 substantially identical to the rod construction in the previously described modification.

A still further modified form of the invention is disclosed in FIGURES 6 and 7 wherein a beam 40 is provided with a plurality of reinforcing rods 41 similar to the reinforcing rods 12 previously described and which are arranged in pairs both laterally and vertically. Bolts or pins 42 are provided transversely of the beam and serve the same function as the bolts or pins 29 and 13. In this case a plurality of laminations 43 serve to make up the composite beam together with a bottom plank 44. The end cap in this construction includes side plates 45, an end plate 46, and a top plate 47. The end cap is secured in position by bolts or screws 48, and the cutaway recess 49 therein is considerably larger than that in the preceding modifications, in order to accommodate the threaded ends of the four rods 41 and their-tensioning nuts 50. This beam is preferably used in heavy duty installations.

While a single rod 12 having a threaded end 12a and a tensioning nut 23 thereon has been hereinbefore described as the'reinforcing member for the above forms of laminated beams, in the modifications of FIGURES 1 and 4, it is to be understood that, if desired, a cable 51, may be substituted therefor. Likewise, a plurality of the cables 51 may be substituted for the reinforcing rods 41 in the modification according to FIGURE 6. In the event that a cable 51, is employed, a connector 52 having a slot 53 therein is affixed to the end of the cable, such affixing being done by inserting the cable through an axial opening 54 in one end of the connector 52, reverting the ends through the slot 53 and then pouring molten lead or the like into the end structure for securely retaining the end of the cable therein. In this case, the opposite end of connector 52, is provided with a threaded bore 55 in which there is received an adjusting bolt 56 provided with head 57, which may be rotated to tension the cable 51 in the same manner that the nuts 23 may tension the reinforcing rods 12.

A further form of reinforcing rod is generally indicating at 60 and has a threaded end 61. For purposes of additional reinforcement, suitable openings are cut into the ends of the beams for the reception of a threaded sleeve 62 having a polygonal end 63, which sleeve receives the threaded end 61 of the rod 60 in order to insure a more secure fastening.

FIGURE 9 discloses a modified form of beam comprised of a plurality of horizontal laminations 11 having longitudinally positioned reinforcing rods 12, cable or cables 51 may be substituted therefor. Dowels 13 are also provided and positioned transversely of the beam above a bottom plank 14', which is grooved longitudinally to receive reinforcing rods 12.

In FIGURE 10 there is shown a side view of a beam similar to that of FIGURE 9 having a modified form of end cap generally indicated at 70. This end cap has a recess 71 in its end plate 75, similar to the recess 21 in the end cap 17 of FIGURE 1, which accommodates a nut 72 for tensioning and securing the end of a rod of cable 77, similar to any of the previously described rods or cables. This rod or cable extends through a beam '78 comprised by horizontal laminations, with the ends of of the boards forming the laminations staggered longitudinally.- In this form of the invention the end cap 70 has a top plate 76 and side walls '73, which latter extend to the bottom of the beam and are joined on the underside of the beam by a bottom plate 74. This bottom plate 74 may rest on suitable I beams, or a cement foundation wall, or the like.

It is to be noted that all rods or cables employed in this invention are to be treated with a rust preventive before fabrication of the beam.

From the foregoing it will now be seen that there is herein provided an improved reinforced laminated beam, truss or rafter construction which accomplishes all the objects of this invention, and others, and having many advantages of great practical utility.

As many embodiments may be made of this inventive concept, and as many modifications may be made in the embodiments hereinbefore shown and described, it is to be understood that all matter herein is to be interpreted merely as illustrative, and not in a limiting sense.

I claim:

1. A vertically laminated reinforced wooden beam having an odd number of laminations including two opposite outer laminations and an internal lamination fixedly secured together as a unit, said beam being approximately rectangular in vertical cross section and having exterior opposed sides, opposed ends, a bottom and a top thus characterizing a longitudinal or length dimension parallel to said sides, and a transverse or height dimension parallel to said ends,

(a) a horizontal pin positioned transversely within said beam and adjacent said bottom, and at approximately the mid length of the latter,

(b) at least one reinforcing rod positioned firmly within only the internal lamination of said beam, and also positioned for a short length beneath said pin and extending upwardly and outwardly in side elevation to adjacent each upper end edge of said beam, each rod end being straight,

(c) an end cap including plate portions fixedly mounted, at each plate portion, by screw attaching means onto each upper end edge of said beam, said caps each including a top plate portion positioned on said top of said beam, an end plate portion connected to the top plate and positioned against an end of said beam, and extending downwardly from the top plate to below the beam mid height, portions of each end plate defining a recess therein with a planar bottom having a hole therethrough for receiving an end of said reinforcing rod in approximately right angular relationship with respect to said bottom,

((1) and a fastening element on each straight end of said reinforcing rod abutting said bottoms of each of said recesses.

2. A vertically laminated reinforced wooden beam having a plurality of laminations including two opposite outer laminations and internal laminations fixedly secured together as a unit,- said beam being approximately rectangular in vertical cross section and having exterior opposite sides, opposed ends, a bottom and a top thus characterizing a longitudinal or length dimension parallel to said sides, and a transverse or height dimension parallel to said ends,

(a) a plurality of pins transversely positioned within said beam and adjacent said bottom, and an opposite sides of the longitudinal mid-section of the beam,

(b) a plurality of reinforcing rods positioned firmly within only an internal lamination of said beam, and also positioned for a short length beneath said pins and extending upwardly and outwardly in side elevation to adjacent each upper edge of said beam, each rod end being straight,

(c) an end cap including a plurality of plate portions fixedly mounted, at each plate portion, by screw attaching means onto each upper end edge of said beam, said caps each including a top plate portion positioned on said top of said beam, an end plate portion connected to the top plate and positioned against an end of said beam, and extending downwardly from the top plate to below the beam mid height, portions of each end plate defining a recess therein with a planar bottom having a plurality of holes therethrough for receiving said plurality of reinforcing rod ends in approximately right angular relationship with respect to said bottom,

(d) a fastening element on each straight end of each reinforcing rod abutting said bottoms of each of said recesses, and

(e) side plates on each side of the beam and connected to said top plate and said end plate of said end cap.

3. A laminated reinforced wooden beam having a plurality of laminations including two opposite outer laminations and internal laminations fixedly secured together as a unit, said beam being approximately rectangular in vertical cross section and having exterior opposed sides, opposed ends, a bottom and a top thus characterizing a longitudinal or length dimension parallel to said sides, and a transverse or height dimension parallel to said ends,

(a)at least one horizontal pin positioned transversely within said beam and adjacent said bottom, and at an intermediate location relative to the length of the latter,

(b) at least one reinforcing rod positioned wholly within the internal laminations of said beam, and also positioned for a short length beneath said pin and extending upwardly and outwardly in side elevation to adjacent each upper end edge of said beam, each rod end being straight,

(c) an end cap, including a plurality of plates fixedly mounted at each end of said beam, said caps each including a 'top plate portion positioned on said top of said beam, an end plate portion connected to the top plate and positioned against an end of said beam, and extending downwardly from the top plate, portions of each end plate defining a recess therein with a planar bottom having at least a single hole therethrough for receiving at least one reinforcing rod in approximately right angular relationship with respect to said bottom,

((1) a fastening element on each straight end of said reinforcing rod abutting said bottoms of each of said recesses,

(e) side plates included on each side of said beam and connected to said top plate and said end plate of said end cap,

plate and said pair of side plates, the longitudinal length of said top plate being greater than the longitudinal length of the bottom plate.

References Cited by the Examiner UNITED STATES PATENTS 327,612 10/1885 Stark 20-92 2,380,953 8/1945 Dubassofi 52225 2,510,958 6/1950 Coif 52-225 2,618,148 11/1952 Reed 52-229 1 2,631,450 3/1953 Lachaise 52-229 3,010,257 11/1961 Naillon 52225 FOREIGN PATENTS 969,001 5/ 1950 France. 1,050,836 9/1953 France. 1,213,358 3/1960 France.

859,522 12/ 1952 Germany.

26,010 1913 Great Britain. 284,016 10/ 1952 Switzerland.

OTHER REFERENCES The Carpenters & Joiners Assistant, call No. TH 5604 N 549; Plate XL relied on.

v FRANK L. ABBOTT, Primary Examiner.

JACOB L. NACKENOFF, EARL J. WITMER,

Examiners.

(f) and a bottom plate vertically supporting each beam 30 end, each bottom plate being connected to said end T. W. FLYNN, R. A. STENZEL, Assistant Examinerst 

1. A VERTICALLY LAMINATED REINFORCED WOODEN BEAM HAVING AN ODD NUMBER OF LAMINATIONS INCLUDING TWO OPPOSITE OUTER LAMINATIONS AND AN INTERNAL LAMINATION FIXEDLY SECURED TOGETHER AS A UNIT, SAID BEAM BEING APPROXIMATELY RECTANGULAR IN VERTICAL CROSS SECTION AND HAVING EXTERIOR OPPOSED SIDES, OPPOSED ENDS, A BOTTOM AND A TOP THUS CHARACTERIZING A LONGITUDINAL OR LENGTH DIMENSION PARALLEL TO SAID SIDES, AND A TRANSVERSE OR HEIGHT DIMENSION PARALLEL TO SAID ENDS, (A) A HORIZONTAL PIN POSITIONED TRANSVERSELY WITHIN SAID BEAM AND ADJACENT SAID BOTTOM, AND AT APPROXIMATELY THE MID LENGTH OF THE LATTER, (B) AT LEAST ONE REINFORCING ROD POSITIONED FIRMLY WITHIN ONLY THE INTERNAL LAMINATION OF SAID BEAM, AND ALSO POSITIONED FOR A SHORT LENGTH BENEATH SAID PIN AND EXTENDING UPWARDLY AND OUTWARDLY IN SIDE ELEVATION TO ADJACENT EACH UPPER END EDGE OF SAID BEAM, EACH ROD END BEING STRAIGHT, 